1. Field of Invention
The present invention relates to non-volatile semiconductor memory apparatuses, and more particularly to non-volatile semiconductor memory apparatuses equipped with charge pump devices that step up power supply voltage.
2. Description of Related Art
Currently, semiconductor memory apparatuses may be classified into a variety of different types depending on their functions. Such semiconductor memory apparatuses includes a memory cell array that is composed of memory cells arranged in a matrix. Generally, in such a device, an address in the row direction and column direction in the memory cell array is designated in performing a reading, programming or erasing operation for each of the memory cells.
By controlling voltages applied to a signal line in the row direction and a signal line in the column direction that are connected to each of the memory cells, a specified memory cell can be accessed such that a specified operation among reading, programming and erasing operations thereof can be performed. In other words, in order to select a specified memory cell, a voltage different from other voltages to be applied to other memory cells may be generated from the power supply voltage and applied.
In recent years, MONOS (Metal-Oxide-Nitride-Oxide-Semiconductor or substrate) type devices have been developed as non-volatile semiconductor devices that are electrically erasable and have non-volatility. A MONOS type non-volatile semiconductor memory apparatus has memory cells each having two memory elements, as described in detail in the article written by Y. Hayashi, et al, 2000 Symposium on VLSI Technology Digest of Technical Papers p. 122-p. 123, which is incorporated by reference in its entirety.
As described in the above reference, to access each of the memory elements of the MONOS type non-volatile semiconductor memory apparatus via signal lines (control lines) that are provided according to the number of the memory cells, not only two kinds of voltage values, but a plurality of kinds of voltage values need to be set for each of the signal lines (control lines). In this case, devices each having a pair of a charge pump circuit that operates with the power supply voltage and a regulator may be prepared in the number of kinds of voltages required for each of the operations of the memory.